Water heater



Dec. 14, 1948.

Filed Nov. 30, 1946 c. M. OSTERHELD 2,456,144

WATER HEATER 2 Sheets-Sheet l INVENTOR.

CLARK M. OSTERHELD BY- I 1943- c. M. OSTERHELD 2,456,144

' WATER HEATER Filed Nov. so, 1946 2 Sheets-Sheet 2 M |5 INVENTOR.

CLARK M. OSTERHELD zrr'y Patented Dec. 14, 1948 WATER HEATER Clark M. Osterheld, Stoughton, Wis., assignor to McGraw Electric Company, Elgin, 111., a corporation of Delaware Application November 30, 1946, Serial No. 713,336

3 Claims.

My invention relates to electric heaters, and particularly to electric water heaters for hot water tanks.

An object of my invention is to provide a relatively simple and novel form of electric tank Water heater.

Another object of my invention is to provide an electric water-tank heater that shall rely on an integral, electric-insulating coating on the resistor for insulating the resistor from its support.

Another object of my invention is to provide an electric heater that shall embody a shroud portion in the supporting means for the resistor.

Other objects of my invention will either be apparent from a description of several forms of device embodying my invention or will be pointed out in the course of such description and be set forth in the appended claims.

In the drawings,

Figure 1 is a view in vertical section through an ordinary domestic water tank having associated therewith an electric heater embodying my invention.

Fig. 2 is a view in lateral section therethrough, taken on the line 2--2 of Fig. 1,

Fig. 3 is a fragmentary sectional view, taken on the line 33 of Fig. 2,

Fig. 4 is a fragmentary sectional view, taken on the line 4-4 of Fig. 2,

Fig. 5 is a fragmentary view of a water tank having associated therewith an electric water heater embodying my invention,

Fig. 6 is a view in section therethrough, taken on the line B6 of Fig. 5,

Fig. '7 is a fragmentary view of a hot water tank having a still further modification associated therewith,

Fig. 8 is a sectional view therethrough taken on the line 88 of Fig. '7,

Fig. 9 is a fragmentary view, in vertical section, of a modification,

Fig. 10 is a fragmentary view, in vertical section, of a still further modification, and

Fig. 11 is a fragmentary view of a resistor conductor which I may use with Fig. 10.

Referring first of all to Fig. 1 of the drawings, I have there shown a domestic hot water tank ll having a lower closure member [3 with a cold water inlet pipe 15 associated therewith. I provide tank I! with an upper closure member I! having associated therewith a hot Water outlet pipe :9. I provide also a mass 2| of heat insulating material such as mineral wool, which is held in proper operative positionaroundtank l l by an outer casing 23.

My electric heater, which is of the clamp-on type, is preferably positioned adjacent the lower end of tank I l but I do not desire to be limitedto the use of a single heater but may also provide an upper heater on the tank.

Heater 2! comprises a helically-wound resistor conductor 29 which is positioned within a substantially semi-cylindrical-tube 3|, this. tube being provided with two sheath or shroud portions 33 and 35. I provide also a relatively small. liner 31, which liner is of arcuate shape in cross section and which is adapted to be positioned between the heating conductor 29 and the outer wall of tank H substantially as shown in Fig. 3 of the drawmgs.

While I may use a metal such as brass or copper for the housing 2.1, as well as for the sheath portions 33 and 35, I may, and prefer, to use aluminum, which aluminum is provided on the inner surface of tubular portion 2'! with an integral, inorganic, heat-conducting, high-temperature-resisting and electric-insulating coating which may be made or provided on the above mentioned portions according to the method set. forth inxU. S. Patent #1,526,127. I prefer to make-the electric insulating coating have a thickness on the order of .001 but the thickness may vary between the limits of .9005, and .0015".

I provide the entire outer surface of the liner 3'! with substantially the same kind of coating as hereninabove set forth in connection with members 21, 33 and 35.

While I may use a standard metallic'resistance conductor for conductor 29 I do not desire. to be limited thereto but may use an aluminum resistance conductor and may provide the entire, outer surface of. said resistance conductor with an electric insulating coating of substantially the same kind as hereinabove set forth in connection with members 3|, 33, 35 and 31.

I may here point out that the dimensionsofthe tubular portion 3! and the thickness and width of liner 3? are so selected that the resistance conductor 29 will be held tightly between tubular member 21 and liner 31.

I hold the tubular resistance conductor supporting members 3!, 33 and 3-5 in close clamping engagement around the outside of tank H as by providing sheaths 33 and 35 with laterally bent.- outend portions 3.9 and 4t, thev length of tubular member '27 and of the sheaths 33 and 35 being made long enough so that a clamping bolt 43: may extend through holes in end portions, 39 and M and be held by nuts 45, having engagementwith a spring 41 positioned between end, portion M and nut 45. The use of a spring 41 will compensate for the greater expansion of an aluminum tubular clamping member around, say, an iron tank so that the heating unit will always be in close heattransmitting engagement with the outer surface of tank I l.

Referring noW to Figs. 5 and 6, I have there shown a plurality of tubular members it connected by an intermediate sheath 5! and having end sheaths 53 and integral therewith, sheaths 5!, 53 and 55 being adapted to be closely clamped against the outer surface of tank 5 I. g

I provide also a liner bl positioned between a resistance conductor 29 in tubular members 49 and the outside surface of tank l i. Substantially the same comments as hereinabove made in regard to the fit of conductor 29 between tubular member 21 and liners 3'! and tank Ii apply also to the structure shown in Figs. 5 and 6.

The same comments as hereinabove made in around a plurality of tubular members 65, having sheath portions El, 559, H and i3 integral therewith, the shape of portions 65, iii, 59, H and 13 being such that tubular member 55 will extend vertically along the outer surface of tank H. I provide a resistance conductor 25) in each tubular member as well as a liner it, the resistance conductor 29 and liner It being so dimensioned in regard to the substantially semi-cylindrical tubular portion 65 that resistance conductor 29 will be held tightly in its proper operative position Within the tubular portion 55.

I may provide three sets of tubular members 65 spaced equi--distantly around the periphery of tank II and may clamp the upper ends of these tubular members 65 and the sheath portions til, 69, H and 13 against the outer surface of tank H by a strap 17, while the lower ends are clamped by a strap 79. Both the upper and the lower straps l1 and T9 are tightly clamped against the outer surface of tank H by bolts 8i extending through end portions 83 and 85 of straps Ti and 19, a nut 81 being provided, as well as a coil spring 89, between the nut and portion 85 of the straps.

The thickness of tubular portions 2?, 49 and 65 may be on the order of .035 and although I give a definite thickness I do not desire to be lim ited thereto since the thickness may vary between, say, the limits of .03" to .04", or may even be slightly larger.

Referring now to Fig. 9 I have there shown a modification of an electric heater embodying my invention and comprising a resistance conductor 9| which is wound first into helical form and is then flattened to substantially the flattened shape shown in Fig. 9. A thin liner 93 is located between the conductor 9i and the tank H and is housed in a tube having sheath or shroud portions 91 and 99. The assembly of tubular member 95 is such that it will hold the conductor 9! and the liner 93 tightly against each other within it. Substantially the same means for holding the heater against the ouside of the tank II as here- I have there shown a tank il having securely clamped thereinbefore described in connection with Figs. 1 to 3 may be used.

Referring now to Figs. 10 and 11, I have there shown still another form of electric heater embodying my invention. A preshaped resistance conductor lili comprising a strip of resistance material provided with lateral slots extending alternately to opposite edges is bent to substantially channel-shape and a thin liner W3 is located between the inturned sides of resistor strip ID! and tank ii. A tube we, having sheaths or shroud portions l @l' and we, holds the preshaped resistor within it and may be held around tank H by the same means shown in Figs. 1 to 3 inclusive.

While I may use ordinary metallic resistor material I may aiso use aluminum resistor material for resistors 9i and iii l, which resistors may have coating over their outer surface of the kind and thickness as hereinbefore described in connection with resistor 29.

The thickness of walls and Hi5, as well as of sheaths 9?, 9i), idl and M9, may be on the order of .035" and the thickness of liners 93 and I03 may be on the order of .015, while the thickness of the eiectric-insulating coating thereon may be on the order of .ilOl" and they may preferably consist of aluminum.

It will be evident that the use of sheath portions tightly engaging the outer surface of tank i I provides a relatively large area for the flow of heat translated in the resistance conductors in the tubular portions so that the temperature gradient will be relatively small. Qne of the drawbacks of an internal electric heater has always been found to be the deposit of lime on the internal heater, particularly when the amount of heat per unit of was relatively large, and in my novel construction no such high or large amount of heat per unit of area does iiow so that there will be no tendency for the deposit of lime on the heater. This absence of deposit of lime is of course also because of the fact that the heater is not in en agement with the water which it is to heat.

Various modifications may be made in the device embodying my invention without departing from the spirit and scope thereof and I desire that all such modifications coming clearly within the scope of the appended claims shall be considered a part of my invention.

I claim as my invention:

1. An electric heater for a hot water tank comprising corrugated strip adapted to be mounted against the outside surface of a tank, a relatively thin liner, of substantially semi-circular shape, in contact with the tank, a helically wound metallic resistor member in said corrugation engaging said liner and said corrugation and means for tightly clamping said corrugated strip against the tank and for clamping said metallic resistor member tightly between said corrugated strip and said liner the outside surface of the tank, the entire outer surface of said metallic resistor member havin thereon an inorganic, high-temperature-resisting, heat-conducting and eiectricdnsulating coating.

2. An electric heater for a hot water tank comprising a corrugated metal strip adapted to be mounted againstthe outside surface of a tank, a relatively thin metal liner, of arcuate shape in lateral section in said corrugation in contact with the tank, a helically wound metallic resistor member-in said corrugation engaging said liner and the inner surface of said corrugation and CLARK M. OSTE'RHELD.

REFERENCES CITED The following references are of record in the of this patent:

UNITED STATES PATENTS Number Name Date 2,237,110 Osterheld Apr. 1, 1941 2,357,906 Osterheld Sept. 12, 1944 10 2,367,368 Osterheld Jan. 16, 1945 FOREIGN PATENTS Number Country Date 287,828 Great Britain Mar. 29, 1928 

